Landscaping and lawn maintenance crews, particularly golf course turf maintenance personnel, use a variety of powered rotary cutters for the rapid removal of grass, weeds, and other low height vegetation. Greensmowers are well known in the turf care industry for cutting grass at the extremely low heights of cut required on golf greens. Modern greensmowers are available in a variety of configurations, including a walk behind type that has a single cutting unit and a riding type that has two or more cutting units. The Greensmaster 3000.RTM. is a riding type greensmower that has three identical transversely mounted cutting units and is manufactured by The Toro Company, the assignee of this invention.
It is especially important that the aftercut appearance and condition of a golf green be relatively free of incongruities or defects left by the cutting unit. "Stragglers" are one type of defect and are grass left uncut or undercut by the cutting unit and thus appear at a greater height than neighboring grass blades. "Ridges" are another type of defect that may be left by multiple cutting unit mowers where the adjacent cutting units are not precisely set to cut at the same height. "Clip" or "bobbing" marks are patterned or wavy turf defects generally transversely aligned to the direction of mower travel, usually resulting from improper machine operation or adjustment. All of these turf defects may influence the appearance or playability of golf course greens. In order to maintain an accurate and true playing green relatively free of these defects, an inspection of the aftercut appearance of the greens may be required. Furthermore, by performing a routine turf inspection and assessment for "stragglers," "ridges" and the like, greenskeeping personnel may be able to discern the efficiency and performance of the greensmowing equipment. A turf inspection for defects also provides an important diagnostic opportunity to reveal improper turf maintenance practices and/or improper machine operation.
In the past, inspection of golf greens for "stragglers," "ridges," and the like that may effect the play of the ball included a primarily visual method wherein the inspector assumed a prone, or generally prone position with his/her head closely adjacent the green and then visually scanned for nearby stragglers or ridges. Inspections at multiple locations inefficiently required the inspector assume the prone position at each location. This inspection method is time-consuming and awkward, and thus has supported a need for a simple and efficient device and method for evaluating turf for defects. In particular, a need has arisen for a device which permits an inspector viewing from above to visually scan for "stragglers," "ridges" or other defects without assuming the prone position. By visually scanning the turf for defects an inspector may qualitatively form an assessment of cutting unit performance. Furthermore, a need has arisen for a device which permits an inspector viewing from above to efficiently quantify the height of such defects.
The prior art discloses an optical tool that permits the visual measurement of turf height from above the device. Referring to FIG. 1, such a device 120, referred to as the OP-TIC-VU-ER and manufactured by Check Signature Incorporated, Shoreview, Minn., is shown. Device 120 includes a body portion 102 and an attached prism portion 106 and is hand-held and carried to a location where measurement is desired. Device 120 is then placed on the turf 112 with knife edge portions 110 and 108 directed downwardly. Device 120 is relatively massive to assist positioning knife edge portions 110 and 108 within the turf 112. A slight downward force may be used to situate the knife edge portions 110, 108 within the turf. Once positioned, the device 120 allows an inspector 100 viewing from above to visually inspect a small patch of the turf 112 through prism portion 106. Prism portion 106 provides substantial internal reflectance of sight line 114 to allow the inspector 100 to compare the turf 112 with measurement indicia 104 to determine the relative turf height 124, as depicted in FIG. 2. Measurement indicia 104 provides the successive vertical distance from knife edge 110, thus the turf height 124 is relative to the knife edge 110. A general limitation of this device 120 is that turf height evaluations made with this device 120 lacks a desired measure of repeatability. The source of the repeatability error is believed by the Applicants to result from the interaction between the knife edge portions 110, 108 and the turf 112. As depicted in FIG. 3, with an enlarged partial view of knife edge portion 110 of body portion 102 within turf 112, the device is shown as having been placed on the turf 112 with a given slight downward force. Body portion 102 may assume a position generally between the green matter portion 200 of turf 112 and a thatch/brown matter portion 202 of turf 112 by application of the slight downward positioning force and the relative large mass of the device 120. However, as a result of the knife edge structure and relative large mass of the device 120, the knife edge portion 110 may easily assume a lower position within the turf when placed with a slightly larger downward force. Such a lower position is evidenced in FIG. 3 with the knife edge portion at 110'. It is believed by the Applicants that a relatively slightly different downward force or technique in placing this device 120 on the turf 112 may lead to a dramatically different turf height measurement of the same turf. The repeatability of such a device 120 is thus heavily dependent on the force and positioning technique when placing the device 120 on turf to be measured. To compare relative turf heights at two locations with this device 120 importantly requires an inspector to duplicate the placement forces and technique when positioning the device. As a result, the accuracy of this prior art device 120 to measure turf height is largely dependent on the skill of and procedure followed by the inspector.
Furthermore, another limitation of prior art device 120 is that the device 120 permits evaluation only of the "local" turf zone 5 situated between the prism portion 106 and body portion 102. Device 120 does not permit the evaluation turf with a "global" zone 7, e.g., that turf situated away from the device 120 and not within the "local" zone 5.
A need exists for a device and method of use to efficiently and accurately view the turf from above for incongruities or defects, such as "stragglers" and "ridges." A need also exists for a device that may be used to visually scan from above for such turf defects within both a "local" and a "global" zone. The present invention addresses the problems associated with the prior art devices and methods.